In the prior art, a touch screen generally includes a display screen and a touch component, wherein the display screen is used for implementing a display function and is generally a thin film transistor liquid crystal display (hereinafter referred to as TFT LCD for short), and the touch component is used for implementing a touch function.
Upon completing the preparation of the touch screen, a pressing test needs to be performed on the touch screen, so as to detect the compressive property and durability of the display screen and the touch component. The pressing test includes a clicking test, a scribing test and a soft pressing test. The clicking test means that, in a state of powering on, each of the test points on the touch screen are pressed separately several times (for example, each test point is pressed 100 thousand times) by using a pressing head, which has a diameter of 5 mm or other size, with a certain force (for example, 2.5 N), and then it is checked whether the appearance and functions of the touch screen are normal. The scribing test means that, in the state of powering on, scribing at each of the test points on the touch screen are performed several times (for example, scribing at each test point 200 thousand times) separately by using a pressing head, which has a diameter of 5 mm or other size, with a certain force (for example, 2.5 N), and then it is checked whether the appearance and functions of the touch screen are normal. The soft pressing test means that, in the state of powering on, a front surface (i.e., a display surface) of the touch screen is positioned facing down, the touch screen maintains perpendicularity to the pressing head, and the touch screen is pushed several times with a certain force (for example, pushing 2000 times with a force of 300 N), and then it is checked whether the appearance, functions and assembling of the touch screen are normal.
After the clicking test, the scribing test or the soft pressing test is performed a large number of times on the touch screen, a surface of a spacer inside the touch screen may be easily damaged, and some particles may fall off the surface of the spacer and fall into the liquid crystal layer, resulting in an abnormal transmission of light occurring at position(s) where the particles fall, thereby producing bright spots, i.e. so-called Zara defects. Thus, after the pressing test is complete, the quality of the touch screen needs to be tested. Specifically, if the number of bright spots is less than a predetermined value, then the touch screen is determined to be qualified; if the number of bright spots exceeds the predetermined value, then the touch screen is determined to be unqualified.
In the prior art, Zara defects presented in the display screen is usually detected visually by a person after the pressing test is complete. However, there are two technical problems as follows in this detection method.
First, criteria for the visual detection vary from person to person, which will easily bring about false detection, missed detection, over detection or the like, resulting in low accuracy of the detection.
Second, the detection is performed after the pressing test is completed, which causes poor instantaneousness of the detection. That is, it is impossible to instantly learn how many times of pressing, scribing or pushing is performed before the number of bright spots exceeds the predetermined value.
Furthermore, in practice, qualification criteria are different for different uses of touch screens, and thus in a case of using the above detection method, it is impossible to determine whether the touch screen meets any other requirement of less strict criteria at the time when the touch screen does not meet the requirement of more strict criteria.